<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/137518>137518</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang] Regression: crash compiling dynamic_cast with final class and optimisation level higher than 0
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          andyg1001
      </td>
    </tr>
</table>

<pre>
    Since clang 19, the following minimal code will crash the compiler when compiled with an optimisation level -O1 or higher:

```
class base { virtual void fn() = 0; };
class test final : base { virtual void fn() { } };
test* new_test() { return new test(); }

test* cast(base* b) {
  return dynamic_cast<test*>(b); // crash here!
}
```

On my PC, I get the error "fatal error: error in backend: Broken module found, compilation aborted!"

See demo here: https://godbolt.org/z/75odnc3Wo

Remove the 'final' on class test and the code will compile again.

</pre>
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